UUID Generator

A universally unique identifier: a 128-bit value written as 32 hexadecimal digits in five hyphen-separated groups, such as 3f2504e0-4f89-11d3-9a0c-0305e82c3301. It is designed so that anything, anywhere, can generate one without coordinating with anything else and still not collide.

Not guaranteed, but the probability is negligible. A random version 4 UUID has 122 random bits, and you would need to generate billions of them before a collision became likely enough to think about. For practical purposes they are unique.

Nothing meaningful. GUID is Microsoft's name for the same 128-bit identifier. The two terms are interchangeable, though Microsoft tooling sometimes prints them in braces and in uppercase.

When an identifier has to be created before it reaches the database, when several systems generate records independently and the results must merge cleanly, when the ID will be exposed publicly and a sequential number would leak how many records exist, or when you are syncing offline clients. Sequential integers remain smaller and index better when none of that applies.

The hyphens are purely presentational, so stripping them saves four characters in a URL or a filename. Uppercase matches the convention in some Microsoft and legacy systems. All three formats represent exactly the same value.

They are generated in your browser from its cryptographic random source, and they never leave your device. Nothing is sent to a server, so no one else ever sees an identifier you generate here.